Dockerfile: update to python 3.4.3 for example/flask_demo.mochi to work

Using pyenv to lay down the ground to have multiples versions of python in the
same image so the image can be used for testing.

Author: tlvu

Dockerfile

@@ -4,17 +4,35 @@ MAINTAINER Long Vu "[email protected]"
 
 RUN locale-gen en_US.UTF-8 && \
     apt-get update && \
-    apt-get install -y python-virtualenv python3-dev libzmq3-dev && \
-    virtualenv -p /usr/bin/python3 /venv/mochi && \
-    . /venv/mochi/bin/activate && \
-    LANG=en_US.UTF-8 pip3 install mochi flask Flask-RESTful Pillow && \
+    apt-get install -y curl git make g++ libbz2-dev libreadline-dev libssl-dev libsqlite3-dev python3-dev libzmq3-dev && \
     useradd mochiuser --create-home
 
+# best-practice: run as user, not root to avoid security exploit
+USER mochiuser
+
+RUN curl -L https://raw.githubusercontent.com/yyuu/pyenv-installer/master/bin/pyenv-installer > $HOME/pyenv-installer && \
+    bash $HOME/pyenv-installer && \
+    export PATH="$HOME/.pyenv/bin:$PATH" && \
+    pyenv init - && \
+    pyenv virtualenv-init - && \
+    pyenv install 3.4.3 && \
+    pyenv rehash
+
+# other python versions, insert another RUN here to re-use existing cache
+
+RUN export PATH="$HOME/.pyenv/bin:$PATH" && \
+    eval "$(pyenv init -)" && \
+    eval "$(pyenv virtualenv-init -)" && \
+    pyenv global 3.4.3 && \
+    pyenv virtualenv venv343mochi && \
+    pyenv activate venv343mochi && \
+    pip3 install --upgrade pip && \
+    LANG=en_US.UTF-8 pip3 install mochi flask Flask-RESTful Pillow && \
+    mkdir $HOME/workdir
+
 # prevent encoding errors
 ENV LANG=en_US.UTF-8
 
-# best-practice: run as user, not root to avoid security exploit
-USER mochiuser
-WORKDIR /home/mochiuser
+WORKDIR /home/mochiuser/workdir
 
-ENTRYPOINT ["/venv/mochi/bin/mochi"]
+ENTRYPOINT ["/home/mochiuser/.pyenv/versions/venv343mochi/bin/mochi"]